System Modelling for Hybrid Solar Hydrogen Generation and Solar Heating Configurations for Domestic Application

Abstract

Hydrogen generation has the potential to deliver an environmentally friendly, low-cost, and renewable energy source. One promising generation method is solar water splitting via a photoelectrochemical (PEC) reaction as an alternative to a combined photovoltaic-electrolyser system. Although PEC technology shows potential, the efficiency of this technology is currently limited by thermodynamics and technical issues in implementation. The development of novel materials is one route for improvements in PEC system efficiencies. In particular, with multiple band-gap electrodes, the thermodynamic efficiency, and so the overall generated hydrogen quantity, can be increased.In the case of applications where there are heating requirements beyond the need to generate hydrogen, there are further options for extracting energy from the solar resource. Longer wavelength radiation not used by the PEC system may be available for use. Just as it is possible to have a photovoltaic-thermal (PV/T) hybrid system which generates both electricity and heat, a PEC unit may also be combined with a solar thermal unit as a hybrid PEC/T system. This combined heat and power (CHP) system will deliver heat directly and also both heat and power through the use of the hydrogen as a fuel in, for instance, a fuel cell.Despite the promise of PEC technology, there is little research in modelling and system simulation and especially for hybrid systems. Systems' modelling is a prerequisite for optimal design, especially for the design and exploration of novel

Design of a Novel Photoelectrochemical Reactor for Hydrogen Production

“…A mix of Dirichlet and Neumann boundary conditions were imposed at the membrane to assure continuity of the electrolyte potential in the three liquid domains as well as the diffusion of the protons. Here, the normal electrolyte current density was assumed to be equal to that of the membrane and from Faraday's law, the proton flux across the membrane was also assumed to be proportional to the current as shown in eqns (26) and (27) respectively. Zero flux was considered for all non-permeable ions.…”

“…A similar approach has also been demonstrated by Ronaszegi. et al [26], where the unabsorbed larger wavelengths are used for thermal applications. All these studies highlight some key and fundamental challenges that still face PEC technology yet giving very useful information that informs future developments.…”